In the field of solid-state cells in which solid electrolytes are used in place of liquid electrolytes, there has been an attempt to focus on electrode active materials and solid electrolyte materials and improve the performance of solid-state cells (for example, Patent Documents 1 and 2).
An all-solid-state cell is disclosed in Patent Document 1, which uses LiCoPO4 as active material.
A technique relating to sulfide-based solid electrolytes is disclosed in Patent Document 2.
Patent Document 1: Japanese Patent Application Laid-Open (JP-A) No. 2009-140911
Patent Document 2: JP-A No. 2015-032529
When LiCoPO4 with an olivine structure and/or LiFePO4 with an olivine structure is used as the cathode active material of a sulfide solid-state cell, there is a problem that the cell is not rechargeable.